The present invention relates generally to a cleaning system for a combine harvester. In particular, the present invention relates to an air diverter for a combine harvester to improve air flow distribution through the cleaning system.
Combines are old and well known in the art. They are available in various designs and models to perform the basic functions of harvesting, threshing and cleaning of grain or other agricultural material.
A typical combine includes a crop harvesting apparatus which reaps mature grain stalks and then feeds the grain stalks to a separating or threshing apparatus. Preferably, the threshing apparatus includes a power-driven rotor mounted inside a stationary cylindrical threshing cage. The rotor threshes and separates the grain from the material other than grain. In such a combine the grain is threshed several times repeatedly, but gently, as it spirals around the rotor and passes through openings in the threshing cage. Essentially, most material other than grain stays within the threshing cage and is directed out the rear end of the combine.
While the threshing apparatus acts to separate a substantial portion of the crop or grain from the material other than grain, some chaff or straw is directed out through the openings in the cage along with the grain and a further cleaning or separating action is required. Further separation is normally achieved in a cleaning section.
The cleaning section includes oscillating cleaning sieves. The cleaning sieves are located below the threshing cage to receive the grain and other material expelled from the cage. The oscillation of the sieves arranges the material in a crop mat or veil on top of the sieves. By forcing a stream of air upwardly through the sieves chaff, straw and other lighter material in the crop mat are separated from the heavier grain and directed out through the end of the combine by the air flow. The heavier seeds or grain fall through the sieves into a collector.
With the increased power and output demands of modern grain combines, cleaning section capacity has become a limiting factor. The most readily achieved method of increasing overall combine capacity is by increasing the width of the combine and the sieves to spread the crop material across a wider area and in a thinner veil. Increasing the width of the cleaning sieves, so as to increase cleaning section capacity, also involves having to modify the air flow across the increased size of the cleaning sieves. The inherently uneven air distribution of known cleaning fans is accentuated by an increase in the width of the cleaning sieves. The uneven distribution of such cleaning fans results in poorer performance of the cleaning system, and can lead to decreases in efficiency and output of the cleaning system.
Thus, there is still a need for a cleaning system and, more particularly, a cleaning system that can more effectively blow air to the sieves of the cleaning system to improve efficiency and output. Such a need is satisfied by a cleaning system having an air diverter for a combine harvester of the present invention.